Since so many AN posts lately involve FIP, I thought I would write a post specifically about it. Before I did some research I knew the acronymn but not the equation. If I was the only one at AN without a clear understanding of FIP sorry to bother you. I'm going to try to keep my editorial opinions about FIP out of this post. Maybe opinions should go into the comments or another post.
According to Wikipedia, in 1999 Voros McCracken invented a stat called "Fielding Independent Pitching". His premise was that pitchers don't have much control over what happens to a ball put in play. The only thing pitchers can really control is walks, home runs and strikeouts.
Here is the formula for FIP(from saberlibrary.com):
FIP = ((13*HR)+(3*(BB+HBP-IBB))-(2*K))/IP+constant
Just for added clarity, HR = home runs, BB = walks, HBP = hit by pitch, IBB = intentional walks, K = strikeouts, IP = not intellectual property, but innings pitched.
The constant is added to get FIP on the same scale as ERA.
I never tried this jump thing before....
“So in short, FIP measures how many earned runs per nine a pitcher would have given up, if performance on balls in play and timing were assumed to be league average.”
Interestingly, to me at least, is that another acronymn thrown around AN a lot is WAR, wins above replacement. For pitchers, it seems that WAR numbers at Baseball-Reference.com are calculated with ERA, while WAR numbers at Fangraphs are calculated using FIP. I could imagine using (ERA+FIP)/2 to calculate WAR, since ERA and FIP are normalized to the same league average value.
FIP punishes walks and home runs(13x) and rewards for strikeouts(2x). A pitcher would have a 0 FIP if all he ever did was give up batted balls that were not homers.
The premise I have seen in comments is that FIP is a less "lucky" number than ERA. I make the case it is different, and that when evaluating pitchers both ERA and FIP should be considered. Oops, I wasn't going to add any opinions.